The present invention relates to an asymmetrical, multi-beam radar sensor having at least two transmitting and receiving patches.
In certain multi-beam radar sensors that have angle evaluation, such as are referred to, for example, in WO 97/02496, the lateral receiving and transmitting paths are arranged so as to be symmetrical with respect to a median plane. In the case of vertical angular detection, the median plane lies in the horizontal direction, and vice versa, in the case of horizontal angular detection, it lies in the vertical direction. For example, due to the preestablished electrical polarization, the three transmitting and receiving patches have the same direction gradient of 45xc2x0 with respect to the horizontal plane (FIG. 4).
In this context, the two lateral transmitting and receiving patches, with respect to their beam center, are nevertheless arranged symmetrically with respect to the central transmitting/receiving patch. A polyrod (rod radiator) is positioned in the beam path for each patch, the lateral polyrods also being arranged symmetrically with respect to the median plane. For the purpose of further bundling the beam, at least one dielectric lens (antenna lens) is connected on the line side, the lens being configured with respect to its geometry so as to be rotationally asymmetrical or centrally symmetrical.
Also in certain multi-beam methods, in which, in place of the planar transmitting and receiving patches (with or without polyrod or superstrat, a planar dielectric plate which is arranged at a specific distance to the sending/receiving patches), sending/receiving arrangements having junctions to horn radiators are used. In this context, in the beam paths of the horn radiators, dielectric materials can be used for geometry reduction and for further beam bundling. In this method, the non-central beam paths from the source to the furthest exit surface of the radar sensor are also arranged symmetrically with respect to the median plane.
Furthermore, European Patent Application No. 0 498 524 refers to an arrangement for a bistatic radar sensor. As characterized, in this radar sensor, an asymmetry may be achieved as a result of the divided arrangement of the transmitting and receiving paths. However, this asymmetry is compensated for by the overall lateral shift of all of the receiving elements such that the central receiving element electrically attains the central position, and the lateral receiving elements cover the same angles, left and right, with respect to the median plane.
The angles are determined for the radar sensor in accordance with certain methods, such as are referred to, for example, in German Published Patent Application No. 195 43 813 (which corresponds to U.S. Pat. No. 5,966,092).
In contrast, the multi-beam radar sensor according to the exemplary embodiment of the present invention is believed to have the advantage that improved angle detection results from the asymmetrical radar arrangement.
It is believed to be particularly advantageous that smaller erratic values are obtained for the signal/noise ratio in a given interference-impacted measurement. It is believed that due to the asymmetry of the corresponding scaling (normalization) curves of left and right beam paths, the result advantageously are fewer similar angle patterns, so that measuring deviations exert a smaller influence. It is believed that the consequence should be fewer false angle assignments.
It is also believed to be particularly advantageous that the desired asymmetry of the beam paths is already achieved due to simple alterations in the arrangement geometry of the transmitting/receiving patches with respect to the median plane.
However, an asymmetry of the beam path may also be achieved because the polyrods are arranged at an unequal distance with respect to the median plane.
An unequal angular position relative to the beam path with respect to the median plane of the outer polyrods as well as the different cross-section geometries are also simple measures that are easy to carry out from the point of view of manufacturing engineering and that are also xe2x80x9ceasyxe2x80x9d to check.
Furthermore, it is believed to be expedient to generate an asymmetrical beam path on the basis of appropriate, dielectric materials for the polyrods. In this manner, it is believed that a precise and reproducible design of the arrangement can be executed, which may be realized in a xe2x80x9csimple mannerxe2x80x9d from the point of view of manufacturing engineering.
It is also believed that a further improvement may be achieved because the dielectric lens is asymmetrically configured for the region of the central beam. As a result, the dielectric lens can be manufactured separately so as to have the desired geometry and can then be assembled along with the further elements of the radar sensor. In this manner, it is believed that various sensor types can also be easily accommodated.
On the basis of the radar sensors according to the exemplary embodiments of the present invention, it is believed that a safer and more reliable angle evaluation can be achieved, as may be necessary, for example, in angle or distance measurement in vehicular radar.